Forced air ventilating heaters



Nov. 5, 1957 T. A. PELSUE ET-AL FORCED AIR VENTILATING HEATERS Filed May 2'7, 1954 2 Sheets-Sheet l Tf/UEWA/V A. Pasu: w

LLOYD W B/PAA JNVENTORS,

BY 38 777W ATTORNEY Nov. 5, 1957 T. A. PELSUE ET AL 2,811,962

FORCED AIR VENTILATING HEATERS Filed May 27, 1954 2 Sheets-Sheet 2 "/0 7710mm A. PELSUE A/VD LLOYD 14/. B/PAA INVENTORS,

1 W/ MW ATTORNEY United States Patent FORCED AIR VENTILATING HEATERS Thurman A. Pelsue and Lloyd W. Braa, Denver, Colo., assignors to The Morrison-Pelsue Co., Denver, C010 a partnership Application May 27, 1954, Serial No. 432,863'

2 Claims. (Cl. 126-410 This invention relates to heaters and more particularly to forced air ventilating heaters.

Subsurface installations of power lines, telephone cables, natural gas and sewer lines has become common practice for the public utilities and telephone companies. Installation of these facilities in underground tunnels has the advantage of protecting them from surface weather conditions which frequently disrupt the service over wide areas. Underground temperatures do not fluctuate over as wide a range as those on the surface and convenient access to the facilities is provided by manholes on the surface. A number of extremely hazardous conditions arise in connection with these subsurface facilities which would not be found in surface installations; therefore, a variety of special safety precautions are necessary for the protection of the public and property located near these installations; and more particularly, for personnel whose duty it is to inspect and repair these facilities.

Underground ventilation is a major problem which cannot be solved by merely leaving the access opening uncovered and depending upon natural ventilation from the surface. Some means for supplementing natural ventilation with forced fresh air ventilation is an absolute necessity in most cases. Quite often the occasion which requires repair of the underground facilities has produced an explosive gas mixture which is extremely hazardous. Efiicient forced air ventilation will of course supply enough fresh air to reduce the relative concentrations of the components to the point where an explosive mixture no longer exists, thereby providing a safe atmosphere in which to Work. Extreme care must be taken, however, that the apparatus for supplying the ventilation is located where it will not in itself ignite the explosive mixtureo It is also quite common to find noxious, although nonexplosive concentrations of gases existing in underground workings. For instance, an insufficient concentration of oxygen may be present due to underground combustion, so that a noxious concentration of carbon monoxide and carbon dioxide may exist and be undetected due to their odorless physical characteristics. Although gas testing equipment is provided for testing the concentration of gases in underground workings before they are entered,

there is always the possibility that these precautions will a not be taken and serious injury or death might result.

Hazardous conditions such as those outlined in'preceding paragraphs, although not existing at the time the underground workings are entered, may be brought about by the ventilating or heating equipment used. In the case of blowers, if the exhaust fumes from the engine are permitted to remain in the underground workings, a noxious concentration of gases may be created. 'Ordinary space heaters, whether or not connected with a blower, have the same limitations and cannot be used underground because the burner quickly exhausts the oxygen and the exhaust gases of combustion are quite dangerous.

i [The problem of heating subsurface installations and also certain other types, such as the aerial tents erected by linemen on telephone poles, raise additional problems. The tunnels are most often damp and extremely uncomfortable for the workmen, especially if the outside air is also cold. Cold, damp underground working conditions have an adverse effect upon the health of the workmen as well as causing decreased efficiency. Apparatus to heat such installations and thereby make them more comfortable requires several important features not found in the conventional space heater or blower. Open flames or even sparks cannot be tolerated underground because of the chance of causing a dangerous explosion. The danger of fire while using conventional heating equipment in telephone linemens tents is also of great importance.

The principal object of the present invention is, therefore, to provide a forced air ventilating heater which may be located above ground and used to force warm, clean air into underground tunnels for the convenience and comfort of workmen without danger of detonating any explosive gas mixtures which may be present or introducing any explosive or noxious mixtures into the tunnels.

Another object of the present invention is to blow out by forced ventilation any explosive or noxious gas mixtures which might exist in underground workings.

A further object of the invention is to provide a heater which, by means of duct work may be used to heat linemens aerial tents located above the ground which might otherwise catch on fire causing serious damage to equipment and injury to personnel.

Other objects will be in part apparent and in part pointed out specifically hereinafter in connection with the description of the drawing which follows, and in which:

Figure l is a side elevation of the forced air ventilating heater of the present invention showing it connected to a tank of liquid petroleum gas;

Figure 2 is an end elevation looking in the direction of arrow 2 of Figure 1 having portions broken away to expose the squirrel-cage blower;

Figure 3 is a diagrammatical view showing the manner in which the ventilating heater is used to force warm ventilated air into underground facilities;

Figure 4 is a section taken along line 4-4- of Figure 2 showing the burner assembly, heat exchanger, and blower;

Figure 5 is a section taken along line 5-5 of Figure 4 showing the construction of the burner assembly and heat exchanger; and,

Figure 6 is a transverse section taken along line 66 of Figure 4 showing the combustion chamber.

Referring now in particular to Figures 1 and 2 of the drawing, reference numeral it) designates an engine of a conventional type provided with an automatic recoil starter 12, which has been adapted for either liquid petroleum gas or gasoline operation. Gasoline tank 14 provides fuel for emergency operation of the engine as the prime source of engine fuel for the engine is liquid petroleum gas taken from tank 16 through the conventional flexible liquid gas hose 13 into fuel line 20. Auxiliary outlet valve 22 is provided in one end of the fuel line for use in operating auxiliary equipment, such as burners for lead pots and the like. A conventional spring loaded diaphragm type pressure regulator 24 is connected in the fuel line. The main fuel line 29 branches to form engine fuel line 26 and burner fuel line 28. Engine fuel line 26 is provided with an automatic zero governor 30 to automatically shut off the flow of fuel into propane carburetor 32 when the engine stops. Burner valve 34 is connected in the burner fuel line 28 in order to supply fuel to the burner for wintertime operation. An automatic gas shut ofi. valve 36 shuts off the burner when it is not lit. Frame 38 supports the engine and related parts. Housing 40 is supported on the frame and con tains the squirrel cage blower 42, the heat exchanger 44, and the burner,acombustionchamber, and related parts which will be described" in detail in connection with FigureSA; 5, andf6} Blower wheel 46 is operatively connected for. rotation on engine shaft 48. The squirrel cage blower. draws air'frforn the'atin'osphere in through air intakein the housing. Handle 52 is secured to the blower housing and engine by means of bracket 54for convenience in carrying the heater.

With particularreference-to Figures 4 and 5, it will be seenfthat'the cofribustion chamber 56 containingthe burner assembly 58 is connected to the heat exchanger 44 in sucha way"thafthe hot'flu'e gases pass up'frorri the. burner assembly into the combustion chamber, throughtlieheat exchanger, and out through the burner fiile 60 tl'1ereby heating the air in'the ventilating air space 62, Blowerhousing, 64, however, cooperates-with the blowerwheel" to dire'c'f'the cold incoming fresh air against the hot surfacesof the combustion chamber and heat exchanger where it is h'ea'tedbefor'e being exhausted'through ai'i discharge 66f The burn'ef'ass'embly'58 is located at the lower end of the'combus'tion chamber 5*6"wherein burner 68 is connectedtothe burner fuel'line' 28. Conventional forced ai'r'in'spirat'ing type burners containing three orifices have been shown in Figure S of the drawing although a number of other'well' known types are suitable. An electric ignitor' 70, whichmayoperate olf'a' constant spark taken fromth'e; engine magneto has been shown in Figure 4 as: the rneansfor'lighting the burner. A thermocouple 72"ispos'itioned above the burner and connected to automatic burner shut off valve 36; Stainless steel tubes 74 positioned above the burner orifices complete the burner assembly. The'upp'er end of the combustion chamber connectswith' the ir'ite'rior of the heat exchanger which consists ofa series of'laterally extending passages 76 communicating with one another and with the combustion chamber and burner flue, but closed off from the ventilatingair'space' 62 bywall portions 78'. Heat'is transferred through the'wall portions 'from'the hot'fiue gases to the ventilating air within ventilating air 'space62' as it passes overithes'e wallsprior. to being' discharged through air discharge) Burne'r'flue' 60 is protected by chimney 80 to prevent persons beingburned on contact'with the hot-flue. A viewingrport 82 is 'provided in the combustion chamber for inspection of the burner assembly.

In Figure 6 will be seen the manner in which the combustion chamber 56'i'is fastened to the housing 40 by means of combustion chamber housing 84. Viewing ports 86 in alignment with viewingport82 of the comb'ustion chamber are provided in the combustion chamber housing 84 and 'housing'4t); A coverplate 88 ismounted for pivotal movement within housings 84 and 40in position to'cover the viewing" ports 86. Lever 90 operates the coverplat'e.

Referring nowto the diagram shown in Figure 3, it will be seen that with an air-hose 92 connected over air discharge 66' with its open end extending down' into a tunnel through access opening 94 on the surface, fresh, warm air may be supplied to the subsurface installati'ons. The ventilating heater is, of'course, positioned above ground where thenoxious' exhaust fumes from the engine and the flue gases passing out through burner flue 60 are exhausted into the atmosphere where they can do no harm. With' the heater itself located above ground, there is no possibility of sparks orflames developed in the heatercausingexplosions. temperatures developed withinthe combustion chamber, burner assembly, andhe'at exchanger areadequate to heat the coldincoming air even underextr'eme weather condi'tionsto a pointwhere' itwill"bedischargedinto the tunnel as warm: healthfull'air"contributing. to the comfort and'well beingpt personnel working'ther'eih. Theb'o'ttoin The high must clearly'in Fig. 4 'to' provide anopening"to supply primary air to the burner assembly. By reason of the fact that the blower while operating maintains the interior of the casing under a positive pressure, primary air will be forced through the burner assembly upwardly in the combustion chamber 56*to supply a sufficient quantity of air for proper combustion of the fuel. However, the burner'uhit is-elfeCtiVely-isOIatedfrom the ventilating air cavity since the forced draft will prevent-fuel from entering-the ventilating" air cavity even under' condttiens'ia which the burner is not ignited.

It is to be understood that the present invention is not intended to be limitedin' any respect" tothe various safety devices which have been illustrated and described in connection with the accompanying drawing which do not directly contribute to the delivery of non-poisonous air into the desired location. These elements while valuable -andneeessaryto'the-safe operation of the engine and fuel lines do not form a part of the present invention, Also, many other suitableprime movers such as electric motors-and other types of engines may be used withequal facility'for the operation of theblower. Such features are intended as being merely illustrative of onemannei' in which aventilating heater ofthe type described herein maybe constructed, and-itis apparent that many modifications'might be made within the skill of the ordinary mechanic while retaining the basic invention.

Havingthus described "the present invention in detail in connection-With the accompanying drawing, it will-be seen-that the manyuseful objects for which it was designed have been achieved; and therefore, we claim:

1. A forced air ventilating-heater comprising a-base, a-housing mountedon said base consisting of a generally rectangular casing including opposite side walls, end walls,

' a top Wallanda bottom wall, one of said side walls having an opening therein adjacent one of said end walls and forming 'a'blower inlet opening, a prime mover mounted on said base and having'a drive shaft projecting intosaidhousing through the opposite side wall, a blower Wheel fixed'to said drive shaft within'said housing-,-an involute-blower wheel shroud fixed to and extending'between'said side walls'in surrounding relation to said blower wheel and encompassing said inlet opening and discharging along the bottom of said housing toward the opposite end wall, a'shell forming an elongate cylindrical combustion chamber disposed within said housingadjacent said opposite end wall, said combustion chamber shellresting'at its lower end on said bottom wall and beingof a diameter substantially less than the distance between said side walls so as'to be spaced therefrom and from the adjacent end wall to allowthe circulation of airtherearound, a burnerm'ounted on said bottom wall for directing fuel upwardly through said combustion chambersheI L- means adjacent said burner for igniting said fuel,- said combustion chamber shell having an opening therein adjacent-said 'burner for the supplyv of combustion-air thereto, the upper end of said combustion chamber extending above the uppermost portion of'said blower wheel shroud, a series of interconnected, vertically spaced, substantially horizontally disposed heat exchanger duets fixed to and in communication with said upper-end of the combustion chamber and with the major portion thereof extending laterally therefrom over said shroud but "in spaced relation thereto and to the top and'isidewalls; said top'wall having an opening thereih above saidcor'nbustion' chamber, a flue carried by said h'eatexchai1ger and extending outwardly of said housing through said top wall opening, at least one of said heat exchangerducts'communicatingwith said flue, and said one endWalI'haVing an opening adjacent its top' in alignrrientwith'said heat exchanger ducts for educting'air froni'thehousin'gjso thatair dis'ch'argedby saidblo'wr through the shroud initially impinges against the lower portionof-the combustion chamber shell and'saidop'osite ehdwall and' tliefiee" passesupwardlyfiwai'd' the upper portion of the combustion chamber shell and the top wall to be finally deflected generally horizontally along said heat exchanger to pass outwardly of said housing through the last mentioned opening.

2. A forced air ventilating heater as defined in claim 1, wherein the lower end of said combustion chamber shell is cut away in a region thereof facing said opposite end wall to form said opening for the supply of combustion air to the burner so that the flow of air created References Cited in the file of this patent by said blower furnishes the combustion air for the 10 215821071 burner.

UNITED STATES PATENTS Tuck June 21, 1938 Bertossa July 4, 1939 Johnston Oct. 27, 1942 Holthouse Aug. 6, 1946 McC-ollum Oct. 29, 1946 Anderson et a1. Jan. 16, 1951 Schultz Jan. 8, 1952 

